4k monitor will only run at 1080p with my 2015 MBP? help please

[wolf1025]

Hi all, first post here, as I wasn't sure where to get help with this. I am running dual monitors with my 2015 MBP (Mojave), computer closed (in clamshell mode). One 27" ASUS from the HDMI port which seems fine, the other from the thunderbolt 2 port > HDMI adaptor > HDMI cable to monitor. I returned my 1920x1080 monitor because at 28" it was pretty grainy and hurt my eyes. So I picked up this 28" ACER KG281K (4k) to run at higher resolution. But Apple display settings wont let me go above 1080p. Whats the issue? Is it the computer, the port? the cable? Wondering if there's a way to make this work above 1080, at least at 2560 x 1440.

Thanks, all, any help is appreciated.

 

[chscag]

Welcome to our forums.

First, try the 28" Acer alone from the HDMI port on your MacBook Pro and check to see if you can get the resolution you desire. That will at least show that it works as it should.

The Thunderbolt 2 outputs on your machine will also take a Displayport connection cable. If the Acer has a Displayport input connection, try that to see if you can get the higher resolution.

It may come down to whether or not your MacBook Pro will support 2 monitors at the higher resolution you desire. I know that your machine is capable of supporting much higher resolutions for one monitor. Here is what Apple says:

Display Support    Supports an HDMI-compatible device, including 4K, while using one Thunderbolt display or support for two Thunderbolt displays

Note that they're referring to Thunderbolt type displays.

 

[wolf1025]

thanks! I tried using the HDMI port into the 4k monitor and it looks MUCH better. Apple isn't telling me what the resolution is, as this is the dialog box under display preferences. But man, SO much better.